PS acceptance and luminosity determination

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Pair Spectrometer acceptances were measured using runs with the total absorption counter. The shapes were compared with the detailed Geant simulation.

The normalization of PS acceptances agrees reasonably well, on the level of 5%, for 2018, 2017, and 2016 TAC runs. Note, the acceptance shape for 2016 data

is different due to the larger PS magnetic field. A good agreement in shapes between the measurements and simulation was observed.

Presentations on TAC measurements

TAC run in January 2018

Comparison of the refined acceptance of 2016, new acceptance of 2017

Preliminary determination of the PS acceptances in 2016

Tac run, May 2018

TAC run, half of the field, Nov 7, 2018

Instructions for obtaining measured fluxes from CCDB

A Python script located in hd_utilities will create a ROOT histogram of the PS tagged flux for a given range of runs.

More detailed instructions are provided in the $README on GitHub. Specifically, the energy binning of the histogram and which polarization orientation is histogrammed can be modified with some command line parameters (see README or script help message). On the ifarm you can setup your environment using the nightly build (example below), or your favorite environment setup script to set the relevant CCDB and RCDB variables.

source /group/halld/Software/build_scripts/gluex_env_nightly.csh 2022-02-18

With your environment set you can run the command to create the flux histogram from the database with the command below

python3.6 $HD_UTILITIES_HOME/psflux/ --begin-run beginRun --end-run endRun